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Title:
AUTOMATIC DENTAL BUR CHANGER
Document Type and Number:
WIPO Patent Application WO/2014/154222
Kind Code:
A1
Abstract:
An automatic electro-mechanical dental bur changer machine that performs robotic mid- procedural bur-changes for a hand-held dental handpiece (1) in a dental clinical setup. When the dental practitioner decides to change a bur (Id) amid his clinical procedure, he has only to remove his handpiece (1) out of the operative field and insert the head (la) thereof into the machine, and thence the machine will fully perform all the steps of bur-changing automatically on behalf of the practitioner without requiring his manual intervention whatsoever. The practitioner can maintain his natural operative-grip of the handpiece (1) seamlessly throughout the process. The machine is composed of a plurality of parts in assembly and the function thereof is automated by means of an electronic- control-circuit which orchestrates the interplay between a plurality of feedback sensors and a plurality of electric actuators that drive the assembly. The mechanical parts of the machine that constitute the immediate mechanical interfaces of the handpiece (1) and the burs during function, namely a handpiece-housing and a bur-holder (11) respectively, are dismountable for sterilization purposes. The bur replacement sequence is inputted into the machine via an electronic user-interface such that the sequence may be entered as single selections before each bur-changing cycle, or, as a preprogrammed sequence entered at the beginning of the clinical session.

Inventors:
SAMODONI TAMER ESSAM (EG)
ELGHAMRAWY MOHAMED SHERIF (EG)
Application Number:
PCT/EG2013/000006
Publication Date:
October 02, 2014
Filing Date:
March 25, 2013
Export Citation:
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Assignee:
SAMODONI TAMER ESSAM (EG)
ELGHAMRAWY MOHAMED SHERIF (EG)
International Classes:
A61C1/14
Foreign References:
US3114964A1963-12-24
US3270416A1966-09-06
US3451133A1969-06-24
US5743734A1998-04-28
Attorney, Agent or Firm:
ELGHAMRAWY, Mohamed, Sherif (475 El-Horreya Street Boulkly, Alexandria, EG)
Download PDF:
Claims:
CLAIMS

That which is claimed is:

1. An automatic electro-mechanical dental bur changer machine which performs robotic mid- procedural bur-changes for a hand-held dental handpiece (1), wherein:

said machine, upon intromission of said handpiece (1) therein, secures said handpiece (1) in position, loosens the friction-grip of the chuck thereof upon the bur (Id) mounted therein, removes the latter bur (Id), inserts another bur therein, re-tightens said chuck to regain the friction-grip thereof upon the latter bur, and finally releases said handpiece (1), all, in a fully-automated sequential process; and

wherein said machine is comprised of a plurality of mechanical parts in assembly wherein the function thereof is automated by means of an electronic-control-circuit (FIG. 12) which orchestrates the interplay between a plurality of electro-mechanical or electro- optical sensors (Sl-3, FO-8, NO-8 FIG. 12) connected to said electronic-control-circuit (FIG. 12) such as to provide machine-state feedback thereto, and, a plurality of electric actuators, comprised of electric motors (3h, 7) and linear solenoids (13), which drive said parts of said assembly through intermediary means of transmission (5, 6, 3f, 3e, 3g, 16d) ; and

wherein a bur-set (llf), composed of a plurality of burs organized in a circular or linear array, constitutes the substitution-pool which comprises all the burs that participate in said process of bur changing; and

wherein the particular mechanical parts of said machine that constitute the immediate mechanical interfaces of said handpiece (1) and said bur-set (llf) during function, a handpiece-housing (15) and a bur-holder (11), respectively, are dismountable and constructed such as to withstand sterilization by autoclave; and

wherein the head (la) of said handpiece (1) is the only portion thereof to be internalized into said machine during function such that the handle (lb) of said handpiece (1) and the hand of the practitioner gripping thereon are well clear of the outer boundary of said machine throughout; and

wherein said machine features an electronic user-control-interface comprising a plurality of keys (BO-8 FIG. 12) connected to said electronic-control-circuit (FIG. 12) such that each key thereof corresponds, electronically, to a particular bur in said bur-set; and wherein the practitioner selects the bur replacement sequence via said user-control-mterface such that said sequence may be entered separately as individual choices before each individual bur-changing cycle, or, as a predetermined bur-replacement-sequence- program entered at the beginning of the clinical session such that the replacement- sequence of burs proceeds automatically step-by-step upon each handpiece- intromission.

2. An automatic dental bur changer machine as in claim 1 wherein said handpiece-housing (15) comprises a cup-shaped feature (15a) formed such that said handpiece-head (la) may be seated tightly therein with virtually no play; and wherein said handpiece-housing (15) is characterized by having a hinged lever (15b) wherein the fulcrum thereof is oriented such that said lever (15b) is turned down by any frontal and/or downwardly pressure such that the counter-hinge teniiinal thereof engages the counter-bur-side of said handpiece-head (la) whereon the mechanism of loosening/tightening the friction-grip of said chuck is located; and wherein said lever (15b) is spring-loaded by means of a torsion spring such that the default state thereof is to stay clear of the insertion path of said handpiece (1); and wherein said handpiece-housing (15) is detachable and re-mountable on said machine by fit-grip attachment/guide means (15c) for accurate reproduction of the position thereof upon each remount.

3. An automatic dental bur changer machine as in claim 2 wherein:

said handpiece-head (la), said chuck thereof in particular, is brought into alignment with the axis, along which bur insertion/dismounting takes place, by means of a fork (16), a part mounted on the frame (3) of said machine such that it may only translate along a bidirectional front-to-rear vector by means of slide-shafts (16c) or guide-rails, whereon said handpiece-housing (15) is mounted and secured in place by said attachment means (15c) such that said fork (16), upon automatic activation of a front-sensor (SI) by the slight pressure of said handpiece-(7 intromission, is driven, by means of an electric motor (3h) controlled by said electronic control-circuit (FIG. 12), inwards to the center of said machine such that it drags said handpiece-housing (15) along with said handpiece-head (la) inserted therein unto bring said chuck of the latter such that the axis thereof becomes coUinear with said bur-msertion/dismounting-axis; and

wherein said frame (3) of said machine features mechanical guide means (3a, 3b) to reproduce proper alignment of said chuck with said bur-insertion/dismounting-axis upon each bur-changing cycle; and wherein said frame (3) also features a passive cam-like-press-slide element (3c) which, as a consequence of said motor-(3A -driven translation of said fork (15), drives said handpiece-housing-lever (15b) thereunder to engage said handpiece-head (la) at the counter-bur-side thereof such as to, simultaneously, secure said handpiece-head (la) in position, in a manner wherein it expresses no play when the chuck thereof attains collinear alignment with said bur-insertion/dismounting-axis, and, actuate said chuck in a manner wherein: the friction-grip thereof is loosened at the beginning of a bur- changing cycle, as said handpiece (1) is being driven towards said alignment with said bur-insertion/dismounting-axis, and tightened as the handpiece (1) is driven in a converse maneuver away from said alignment with said bur-insertion/dismounting-axis at the end of the bur-changing cycle; and

wherein an electro-mechanical or electro-optical rear-sensor (S2) indicates, at the end of said inward-translation of said fork (16), to said electronic control-circuit (FIG. 12) the establishment of said collinear alignment between the axis of said chuck and said bur- insertion/dismounting-axis; and

wherein said front-sensor (SI) indicates the end of said bur-changing cycle, at the end of said outward-translation of said fork (16), to said electronic control-circuit (FIG. 12) such that said machine is reset and returns to the default standby state thereof.

4. An automatic dental bur changer machine as in claim 3, adapted with provisions such as to render machine-operation compatible with conventional Pushbutton-Type dental handpieces wherein:

said passive cam-like-press-slide element is constituted by a press-wheel (3c), a free-rolling passive cylinder mounted on a flange extending forwardly from said frame (3), situated such that said handpiece-housing-lever (15b) is slide-pressed thereunder when said handpiece-housing (15) is translated inwards towards the machine-center; and wherein said handpiece-housing-lever (15b) features on the lower surface thereof a small rubber pad which renders any contact with the push-button (lc) of said handpiece (1) nonabrasive, and wherein, on the top surface thereof, said handpiece-housing-lever (15b) features a small bump-like projection which, at the end of said inward translation of said handpiece-housing (15), comes to rest exactly under said press-wheel (3c) such that the pressure exerted by the latter is transmitted through said bump-like projection to actuate the chuck of said handpiece (1).

5. An automatic dental bur changer machine as in claim 3, adapted with provisions such as to render machine-operation compatible with conventional Wrench-Type dental handpieces wherein:

said passive cam-like-press-slide element is constituted by a flange of an inverted-L-shaped cross-section which extends forwardly from said frame (3) and comprises two perpendicular flat sheets, a vertical-friction-rack (3k) and a horizontal-press-flange (3j); and

wherein said handpiece-housing-lever (15b) features a spring-loaded-wrench-bar (15e) mounted thereupon perpendicularly such that the latter expresses full rotary freedom with respect to the former by means of a supporting ramp-bracket (lSd) wherein said spring-loading is directed axially; and

wherein said horizontal-press-flange (3j) comprises a front-to-rear clearance slot of enough width such that said spring-loaded-wrench-bar (15e) may pass therein without interference as said ramp-bracket (ISd) slides under said horizontal-press-flange (3j); and

wherein the assembly relations of said elements is such that, when said handpiece-housing- lever (15b) is in full engagement with the head (la) of said handpiece (Iw), the top surface of said ramp-bracket (15d) attains a coplanar relation with the lower surface of said horizontal-press-flange (3j) and, simultaneously, said spring-loaded-wrench-bar (15e) attains coaxial alignment with the wrench-socket (le) of said handpiece (Iw); and wherein said spring-loaded-wrench-bar (15e) features a coaxial rubber-wheel (15f) mounted thereupon, such that the rotary motion of the former and the latter are coupled with no relative freedom, and arranged such that the circumference thereof is tangential to the inner surface of said vertical-friction-rack (3k); and

wherein said components are situated in assembly such that the mechanical interplay of said rubber-wheel (15f) and said vertical-friction-rack (3b) occur, simultaneously, with the mechanical interplay of said ramp-bracket (15d) and said horizontal-press-flange (3j) such that, upon said translation of said handpiece-housing (15), said ramp-bracket (15d) is driven to slide under said horizontal-press-flange (3j) while said rubber-wheel (15fi rolls, by friction, upon said vertical-friction-rack (3k) in a manner such that said handpiece (Iw) is secured and the chuck thereof is actuated simultaneously.

6. An automatic dental bur changer machine as in claim 3, adapted with provisions such as to render machine-operation compatible with conventional Push-Out-Pin-Type dental handpieces wherein:

said passive cam-like-press-slide element is constituted by a horizontal-press-flange (3j) extending forwardly from said frame (3) wherein said flange comprises a front-to-rear clearance slot; and

wherein said handpiece-housing-lever (15b) features a spring-loaded-push-out-pin mounted thereupon perpendicularly with the aid of a ramp-bracket (lSd), wherein said spring- loaded-push-out-pin may pass through said clearance slot as said ramp-bracket (ISd) slides under said horizontal-press-flange (3j); and

wherein the assembly relations of said components is such that, when said handpiece- housing-lever (15b) is in full engagement with the head (la) of said Push-Out-Pin-Type handpiece, the top surface of said ramp-bracket (15d) attains a coplanar relation with the lower surface of said horizontal-press-flange (3j) and, simultaneously, said spring- loaded-push-out-pin attains coaxial alignment with the push-out-pin-socket of said handpiece; and

wherein the force exerted by the spring used in said spring-loaded-push-out-pin is less than what is required to evacuate the bur inserted into said handpiece such that the evacuation of said bur is achievable only if said force is adjunct with means of non- passive actuated bur dismounting.

7. An automatic dental bur changer machine as in claim 3, adapted with provisions such as to render machine-operation compatible with conventional Lever-Type dental handpieces wherein:

said handpiece-housing-lever (15b) features a hinged-arm wherein the fulcrum thereof is perpendicular to the top side of the former such that said hinged arm lays in the same plane and orientation as to engage the lever of said Lever-Type-handpiece when said handpiece-housing-lever (15b) engages the head (la) thereof; and

wherein said hinged-arm has a cam-end and an engagement-end wherein, said cam-end features a passive roller, and said engagement-end features temporal-attachment means, and wherein said hinged-arm is spring loaded by means of a torsion spring; and wherein said passive cam-like-press-slide element is constituted by a deflection cam- surface, or roller element, with an orientation such as to drive said hinged arm into actuating said lever of said Lever-Type-handpiece thusly actuating the chuck thereof as said handpiece -housing (15) is translated.

8. An automatic dental bur changer machine as in claim 4, or, claim 5, or, claim 6, or claim 7, wherein:

a vertical main-shaft (4) is mounted on the frame (2) of said machine by means of one or more bearings (brl, br2), wherein the top end of said main-shaft (4) is threaded as to serve as a lead-screw (4b); and

wherein an electric-motor (7) fixed on said f ame (2) is setup so as to drives said main-shaft (4) through intermediary means of transmission (5, 6) wherein said electric-motor (7) is connected to, and controlled by, said electronic-control-circuit (FIG. 12) such as to drive the process of bur alignment and the insertion/dismounting thereof; and

wherein a spiral-cam-plate (8), a flat cylindrical plate comprising a spiral-groove (8a) and a small singular circumferential flange (8b), is fitted coaxially upon said main-shaft (4) with full mutual rotary coupling; and

wherein a stage (9), a compact cylindrical part, is coaxially mounted on said main-shaft (4) by means of a bearing (br3); wherein said stage (9) features an array of isometric circumferential flanges (9b) serving as angular-step stoppers, and, a spiral-cam-follower (9d) which follows said spiral-groove (8a) while sliding radially in a guide slot (9c) thereof situated on the underbelly of said stage (9) such that said spiral-cam-follower (9d) braces said spiral-cam-plate-circumferential-flange (8b) upon contact by temporal- attachment means, and, a circumferential switch-cam (9a) having a singular radial crest, and, a plurality of guide-pins (9e) extending perpendicularly from the top surface of said stage (9); and

wherein a subgroup of said machine-state sensors is constituted by two circular arrays of roller-microswitches (F0-F8, N0-N8) arranged such that the rollers thereof establish a circumferentially isometric formation in concentricity with said switch-cam (9a) such that the rotation of the latter actuates said roller-microswitches (F0-F8, N0-N8) sequentially one at a time wherein said two arrays have a relative phase angle difference such as to maximize the roller-to-roller-angle, and wherein said two microswitch arrays are connected to said electronic-control-circuit (FIG. 12) so that the latter is incrementally updated with the angular-sectorial position of said stage (9); and wherein an angular-limiter part (12) is mounted on said frame (2) by means permitting relative motion in an orientation such that said angular-limiter (12) may be actuated into engaging said circumferential flanges (9b) of said stage (9) such as to stop the latter at specific angular steps along the rotary course thereof, said angular-limiter (12) having means of temporal attachment to said circumferential flanges (9b), and wherein a linear solenoid (13), controlled by said electronic-control-circuit (FIG. 12), actuates said angular-limiter (12); and

wherein a platform (10), a compact cylindrical part, is mounted concentrically upon said lead-screw section (4b) of said main-shaft (4) such as to translate vertically upon rotation of the latter, wherein said platform (10) features guide-holes (lOe) wherein said guide- pins (9e) of said stage (9) are inserted so as to couple the angular positions thereof in a manner which permits relative vertical translation between said platform (10) and said stage (9) yet inhibits any relative rotary freedom; and

wherein one member of said machine-state sensors is constituted by a microswitch (S3) which is connected to said electronic-control-circuit (FIG. 12) and mounted on said frame (3) at a position wherein said microswitch (S3) is actuated when said platform (10) reaches the top limit of the stroke thereof; and

wherein said bur-holder (11) is composed of two circular plates, a top plate and a bottom plate, joined by a central tubular segment, wherein said bur-holder (11) is mountable/dismountable upon the top surface of said platform (10) by temporal- attachment means which also serve as precision-emplacement elements comprising insertion-guides (10b, lie), a key (10c), and a bur-holder-lock lever (14); and

wherein said top plate of said bur-holder (11) features a bur-gripping-plate (lib) fixed thereupon and whereon said bur-set (llf) is mounted such that the axes of the burs comprising said bur-set (llf) lay in a virtual cylindrical surface wherein said bur- insertion dismounting-axis is an axially-tangential element thereof, and wherein said top plate of said bur-holder (11) also features a circular array of alignment-holes (lid) arranged such that each hole thereof is in radial alignment with a corresponding bur in said bur-set (llf), wherein said alignment holes (lid), during function, accept the repeated insertion of a frame-mounted alignment-pole (3a) which, in conjunction with other guide means (3b), insures the accurate reproduction of coaxial alignment between each bur of said bur-set (llf) with the axis of said chuck of said handpiece.

Description:
Automatic Dental Bur Changer

TECHNICAL FIELD

The invention relates to the field of clinical operative and surgical dentistry wherein the use of a dental handpiece is an essential procedural requirement. More particularly, the invention relates to robotic electro-mechanical machines which assist the dental practitioner in the process of bur changing during climcal dental procedures.

BACKGROUND ART

The drilling function of a dental handpiece, accompanied by dental burs, constitutes the foundation of clinical operative dentistry and is categorically indispensable regarding many dental surgical procedures. The dental high-speed pushbutton-handpiece dominated dental clinical practice because it simplified the process of bur-changing in comparison with other types of dental handpieces such as the, previously popular, Wrench-type handpiece and the, currently rare, push-out-pin-type handpiece. But, despite the added convenience of a pushbutton feature, the process of bur-changing with the utility thereof remains a demanding manual process that requires concentration, manual dexterity, and patience. Throughout certain clinical procedures, the accumulative time expenditure on numerous mid-procedural bur-changes can be considerable. Additionally, when numerous bur-changes interrupt a clinical operative procedure, the resultant recurrent distraction of the practitioner from his operative field can prove to be taxing in many ways. Evidently, a dental practitioner can always benefit from any bettered assistance in the process of mid-procedural bur-changes such as to niinimize the effort and time associated therewith.

The following earlier patents are representative of pertinent prior art :

U.S. Pat No. 3270416 ; U.S. Pat. No. 3451133 ; U.S. Pat. No. 5743734. DISCLOSURE OF THE INVENTION

As part of the general need to improve the quality of dental clinical performance, there is a continuous demand for any improvement that could minimize the practitioner's distraction, labor, and time spent on bur-changing during dental clinical procedures.

The process of mid-procedural bur-changing can be divided into two components; the first component is a purely mental process wherein the practitioner has to know the type of burs, and the sequence thereof, required to perform the clinical procedure at hand; the second component, which is purely physical, is a dull repetitive mechanical process wherein a bur is ejected from the dental handpiece and another bur inserted therein to replace the former. The purpose of this invention is to fully automate the latter process such that the dental practitioner, during a clinical procedure, is fully relieved from having to spend any manual effort in changing the bur on his handpiece.

The present invention is an automatic, electro-mechamcal, dental bur changer machine that performs robotic mid-procedural bur-changes for a hand-held dental handpiece in a dental clinical setup such that, said invention, fully executes all the mechanical steps of bur-changing on behalf of the dental practitioner without requiring his manual intervention whatsoever.

Henceforth, as may be understood from context, and, unless otherwise specified, an embodiment of the invention may be referred to as "machine".

In all embodiments of the invention, the machine comprises an easily-detachable handpiece- housing which functions as the immediate interface between the machine and the handpiece. Said handpiece-housing serves the machine as to mechanically secure the handpiece throughout the bur-changing cycle in a position, and orientation, compliant with the functional tolerances of the machine and, thus, the proper function thereof. Said handpiece-housing is the only part in the machine that comes into physical-surface-contact with the handpiece. Another easily- detachable element, in all embodiments of the invention, is a bur-holder which carries an array of burs that constitutes a bur-set from which, and to which, bur replacements are made. The main function of the bur-holder is to keep the position and orientation of each bur, of all burs composing said bur-set, within the functional tolerance range for proper machine-function. Said handpiece-housing and said bur-holder are the only machine-parts that come into contact with potentially infectious biological matter such as saliva, blood, and tissue debris, therefore, those two parts, exclusively, have to be detached and sterilized before clinical reuse. Consequently, said handpiece-housing and said bur-holder must undergo the same sterilization and replacement protocols, as other instruments do, in a dental clinical setup.

In any bur-changing cycle, two burs participate in the process; the first, is the bur initially mounted on the handpiece at the onset of the process, said bur will, henceforth, be referred to as the bur "to be replaced"; the second, is the bur chosen from amongst the bur-set to replace the first, and , henceforth, shall be referred to as the "replacement-bur".

The machine, in all embodiments of the invention, is, by default, in a state of standby, awaiting the intromission of the handpiece-head therein. Whilst the machine is in the latter state, one bur is electronically selected, by means explained hereinafter, as the replacement-bur for the next cycle. When the operator decides to change burs amid his clinical procedure, he has only to take his handpiece out of the operative field (the patient's mouth) and insert the head of his handpiece into the machine. Thence, the machine will, automatically, change the bur and, then, release the handpiece with the new replacement-bur thereupon. Therefrom, the practitioner may return his handpiece to the operative field once more and resume his clinical procedure.

Throughout any bur-changing cycle, only the head of the handpiece is internalized into the machine, and the practitioner's hand stays well clear therefrom. Thus, the operator's natural operative-grip of the handle of the handpiece needn't be altered in anyway before, during, or after the bur-changing cycle. Thus, the practitioner's grasp of the handpiece seamlessly remains the same throughout the process.

In a typical embodiment of the invention, once the operator inserts the handpiece into the machine, the insertion event is detected thereupon, via electro-mechanical or electro-optical sensors, and the bur-changing cycle is automatically initiated, and, forthwith, the following sequence of mechanical tasks commence robotically: The machine, as a first step, presses the handpiece-pushbutton, by means of an arrangement of mechanical parts in assembly, thereupon, securing the handpiece in position and, concurrently, relieving the bur, to be changed, from the friction grip of the chuck. Then, the machine grasps the bur, to be changed, and removes it from the handpiece. Thence, the latter bur is returned to its original position in the bur-set. After that, the machine aligns the replacement-bur and inserts it into the handpiece-chuck. Then, the machine releases the handpiece-pushbutton such as to allow the chuck to grip the replacement- bur mounted therein. Finally, the machine releases the handpiece for the operator to resume his clinical procedure.

All thus far mentioned mechanical steps are orchestrated by an electronic control circuit which regulates the interplay between: a plurality of electric actuators driving the machine, such as electric motors and linear solenoids, and the feedback signals received from a plurality of electro-mechanical, or electro-optical, sensors setup in the machine for indicating the state thereof.

All embodiments of the invention comprise an electronic user-control-interface whereon the operator inputs bur-selections. In one embodiment, the user-control-interface is a simple keypad wherein each key corresponds to a particular bur located within the bur-set. Any time before inserting the handpiece into the machine, the operator can select a replacement-bur by pressing its corresponding key. Alternatively, the operator may input a programmed sequence of bur replacements at the beginning of the clinical session, in which case, the operator will not be required to use the control-interface again throughout the remainder of the session; and the machine, upon each insertion of the handpiece therein, lines up the next replacement-bur according to the program saved in the machine's memory.

The concept of the present invention is applicable to all four currently-available types of commercial dental handpieces, conventionally known as, pushbutton-type, wrench-type, push- out-pin-type, and lever-type, dental handpieces; the four types differ in the mechanism by which the friction-grip of the chuck thereof is actuated; in other words, said four types require different provisions for engaging the chuck and tightening/loosening the friction-grip thereof. Any given embodiment of the invention encompasses four sub-variants thereof which cover all operability requirements of said four types of dental handpieces such that each variant differs from the other three, only, in design provisions for chuck-actuation.

The present invention does not purport to target broadly the applications of automatic instrument change in surgical medicine, but rather, it is directed specifically to the concept of dental mid-procedural automatic-bur-changing for a hand-held dental handpiece. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings presented herewith are illustrative of the preferred invention- embodiment which is described in detail hereinafter and shall, henceforth, be referred thereto as "the machine". Some drawings may show some broken parts, recognized by the presence of crooked break-lines, to reveal underlying structures in the assembly.

FIG. 1 is a front perspective view of the machine illustrating the state thereof when the handpiece is ready to be withdrawn therefrom at the end of a bur-changing cycle.

FIG.2 is a cropped rear perspective view of the machine in the same state as in Fig. 1.

FIG.3 is a cropped top perspective view of the machine illustrating the relation of various parts in the assembly.

FIG. 4 is a perspective view of some isolated parts illustrating the manner of

mounting dismounting the handpiece-housing and the bur-holder.

FIG.5 is a perspective view of a handpiece about to be inserted into, or just withdrawn from, the handpiece-housing.

FIG.6 is a magnified detail-view of a location outlined by the detail-circle A in FIG. 7.

FIG. 7 is a perspective view illustrating the state of the machine and the handpiece amid a bur- changing cycle at the instant where a bur is about to be dismounted from, or was just mounted on, the handpiece; with an angle of viewing that shows the underbelly of the handpiece-housing and the bur-holder.

FIG. 8 is a front view of the machine when it is in the same state as in Fig. 7.

FIG.9 is a sectional view, taken along the bisecting mid-plane of the machine indicated by the section-line B-B in Fig. 8, showing the state of the machine when it is in the same state as in Figs. 7-8; also illustrating the position of the practitioner's hand during machine function. FIG. 10 is a cropped perspective view showing the top of the machine when it is in the same state as in Figs. 7-8.

FIG. 11 is a sectional view taken along the section-line C-C in Fig. 8. FIG. 12 is the circuit diagram of the machine's electronic-control-circuit.

FIG. 13 is a perspective view illustrating some modifications made to the embodiment shown in Figs. 1-10 such as to constitute a variant thereof which operates with a wrench-type dental handpiece, in contrast to the pushbutton-type dental handpiece featured in Figs. 1-3, 5-10.

FIG. 14 is a perspective view illustrating the machine with the same provisions as in Fig. 13 wherein the chuck actuation elements have fully engaged the handpiece-head and relieved the shank friction-grip thereof.

FIG. 15 is a cropped top view illustrating the same state as in Fig. 14. FIG. 16 is a sectional view, taken along the section-line D-D in Fig. 15.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF

THE INVENTION

In this embodiment of the invention, the first variant is customized to perform bur-changes on a pushbutton-type dental handpiece 1 which comprises a handle lb, a push-button lc, a head la, and a mounted bur Id thereon; the latter is a member of an array of eight burs constituting a pool of replacements referred to, henceforth, as the bur-set llf. The general architectural concept of this embodiment is to perform a robotic bur-changing process by means of a multi-layered group of rotary parts sharing the same axis of rotation while having various modes of relative freedom of rotary-motion.

A frame, composed of a bottom-piece 2 and a top-piece 3 fastened together, keeps all parts, directly or indirectly, at their respective places in the assembly. A main shaft 4, which constitutes the central axis of the machine, is mounted vertically on the frame-bottom-piece 2 with complete rotary freedom with respect to the latter by means of two bearings brl and br2. A primary gear 5 is mounted on the main shaft 4, with full rotary coupling, at a hub section 4a thereof between the bearings brl and br2. The main shaft 4 is driven, through the primary gear 5, by a primary pinion 6 which is mounted on a primary motor 7 which, in turn, is fixed to a motor-bracket feature in the frame-bottom-piece 2. At a higher location to the bearing br2, a spiral-cam-disk 8 is mounted on the main shaft 4 with full rotary coupling between them as shown in FIGS. 8-9. The spiral-cam-disk 8 comprises a spiral-cam-groove 8a and a cam- leader-flange 8b which is a small magnetized plate extending vertically in co-planarity with the central axis of the machine as shown in FIGS. 1 & 8. Above the spiral-cam-disk 8, another disk-like part, called the stage 9, is mounted on the main shaft 4 by means of a bearing br3 thus allowing the stage 9 and the main shaft 4 to rotate freely relative to each other. The stage 9 comprises the following features: a central switch-cam 9a; an array of nine circumferential flanges, called circumferential-colliders 9b; a radial-rail 9c, of dovetail cross-section in this particular embodiment, along with a cam-follower 9d which is free to translate radially therein; and three vertical guide-pins 9e. The function of the stage 9 and the mentioned features thereof shall be explained hereinafter. Above the bearing br3, the main shaft 4 is threaded all the way to its top free end to compose a right-handed lead-screw 4b whereon a rotary part, called the platform 10, is mounted such that the latter comprises the complementary internal threading of the former. The platform 10 comprises the following functionally-essential features: a bur- holder-tray 10a, insertion-guides 10b, a bur-holder-key 10c, a hinge-pin lOd, guidance-holes 10c, and a switch-rim lOf; the function of the platform 10 and the mentioned features thereof shall be explained hereinafter. Mounted on top of the platform 10, during function, is a bur- holder 11 which is composed of a body 11a and a bur-gripping-plate lib, made of sheet spring metal, fastened thereon by snap action. The bur-holder-body 11a is also equipped with a manipulation handle 11c extending therefrom to aid in insertion and removal of the bur-holder, respectively, at the beginning and the end of a clinical session as, best, illustrated in Fig. 4. The bur-holder 11 is devised to be dismountable because the practitioner will have to sterilize the bur-sets 11 before reuse with another patient. The sterilization of the latter is achieved by autoclaving the bur-holder 11 along with the bur-sets 11 mounted thereupon together. The bur- holder-body 11a also comprises an isometric circular pattern of nine alignment-holes lid wherein one of the holes, the one corresponding to the blank bur-less sector of the bur-gripping- plate lib, is continuous with a guidance-slot lie which serves as a guidance-slot for proper alignment of the bur-holder 11 when it is mounted at the beginning of the clinical session.

The frame-top-piece 3 comprises the following features: an alignment-pole 3a; an alignment- box 3b; a, free roller, press-wheel 3c mounted on a horizontal flange which extends in a frontal direction above the alignment-box 3b; a couple of holes with slide bushings therein, dubbed fork-slides 3d, extend from the front to the rear with coplanar horizontal axes; a group of gears, mounted on an arrangement of poles, constituting a gear-box 3e which is driven by a secondary-pinion 3f and terminates its transmission through a fork-pinion 3g; a motor bracket which houses an electric secondary-motor 3h which, in turn, drives the gear box 3e through the secondary-pinion 3f.

A radial-angular-limiter 12, a small magnetized tablet which slides radially with respect to the main rotary axis of the machine, is coupled to the plunger 13a of a spring- 13b-loaded pull-type linear-solenoid 13. There is a slide groove in the frame-bottom-piece 2, having dovetail cross- section in this particular embodiment, such that the radial-angular-limiter 12 slides therein at 30° angulation with respect to a translated front-plane that passes through the main rotary axis of the machine as depicted in Fig. 11. A bur-holder-lock 14, an arch-shaped lever with inner circular grooves, is mounted on the hinge-pin lOd of the platform 10 such that it can be turned to lock and secure the bur-holder 11 in place during function. Once turned to secure the bur- holder 11, the bur-holder-lock 14 is held in position magnetically; the latter is also equipped with a handle 14a to aid the operator in opening it when the bur-holder 11 is to be dismounted from the machine.

A handpiece-housing 15 functions as the mechanical interface between the handpiece 1 and the remainder of the assembly such as to actively secure the handpiece-head la, reproducibly each time it is inserted therein, in a position that complies with the functional tolerance of the assembly. The handpiece-housing 15 is comprised of a dock 15a, which constitutes the base thereof, and a press-lever 15b which is hinged on the latter and serves as a mechanical interface between the press-wheel 3c and the push-button lc during function. The dock 15a has an internal cup-shaped geometry which accurately complements, in a negative reproduction, the geometry of the handpiece-head la such that latter does not exhibit any play when it is seated therein. The dock 15a also comprises certain attachment features, positioning-holes 15c in this particular embodiment, which serve as means of easy attachment/detachment of the handpiece- housing 15 with the remainder of the assembly as will be explained hereinafter. Like the bur- holder 11, the handpiece-housing 15 is devised to be a detachable interface so that it can be sterilized before reuse in consecutive clinical sessions.

An H-shaped part, dubbed the fork 16, is the part whereon the handpiece-housing 15 is mounted/dismounted, and thus, is the part that directs the motion of the handpiece-head la upon insertion of the latter. The fork 16 comprises the following features: two positioning-pins 16a, which, upon insertion of the handpiece-housing-dock 15a thereon, guides the latter to its proper horizontal position and, through slight friction, maintains its vertical position when the handpiece 1 is withdrawn from the machine at the end of a bur-changing cycle; a horizontal-bed 16b whereon the handpiece-housing-dock 15a rests such that the exact vertical position and level of the latter is maintained by the former; two slide-shafts 16c, which are two poles that slide linearly through the fork-slides 3d; a fork-rack 16d through which the fork-pinion 3g drives the translation of the fork forwards and backwards; a switch-toggle-pin 16e.

There is a plurality of microswitches situated at several key-positions throughout the assembly, the purpose thereof is to provide machine-state feedback-signals to the electronic control-circuit illustrated in Fig. 12.

On the top surface of the frame-top-piece 3 are two opposing microswitches, SI and S2, situated at a forward position and a rear position, respectively, such as to be toggled by the fork-switch-toggle-pin 16e at the forward and backward limits of the stroke of the fork 16. Another, solitary, microswitch S3 is positioned vertically, wherein the bisecting mid-plane thereof is parallel to the main rotary axis of the machine, such as to be toggled by the switch- rim lOf as the platform 10 reaches the top limit of its vertical stroke. Around the switch-cam 9a are two circular arrays of wheel-lever-microswitches, each array is composed of nine microswitches which have an isometric circumferential distribution such that the lever-wheels thereof are centripetally directed; the first array of nine microswitches, F0 - F8 clock-wisely, is situated on top of the second array, NO - N8 clock-wisely, with an angular phase shift of 20°; both arrays are held in place by means of a circular switch-rack 17. The positions of all mentioned microswitches in the assembly are indicated in the drawings, FIGS. 2-3 & 10-11 , and the electronic connections thereof to the electronic control-circuit are illustrated in the mechanical parts related thereto, such that the process of sliding a bur in-and-out of the handpiece-head la becomes a smooth mechanical process which complies with the functional tolerance of the assembly. Such alignment is achieved by the interlocking of the rear side of the handpiece-housing-dock 15a with the alignment-box 3b. Concurrently, the nandpiece-housing- press-lever 15b is tippled and pressed-down by the press-wheel 3c thus the handpiece-push- button lc is depressed thereunder and the handpiece-head la is secured in place by the pressure thereupon as shown in Fig. 10. At the begging of a clinical session, the, initially empty, handpiece is inserted for its first mount wherein the handpiece is entered to meet the bur-holder 11 at the empty sector thereof which corresponds to the sector wherein the guidance-slot lie is located. If the bur-change is mid-procedural, then the handpiece 1 will be inserted with a mounted bur Id therein, and, the handpiece 1 will, then, meet the bur-holder 11 at the sector that corresponds to the location of said mounted bur Id; once the handpiece-head la is at its final position at the end of the rear-stroke of the fork 16, the mounted bur Id is grasped by its respective pincers on the bur-gripping-plate lib.

Another response to the closing of the backward-fork-stroke-limiter S2 microswitch, is the activation of the primary-motor 7 which, through the intermediary primary-pinion 6 and primary-gear 5, drives the main-shaft 4 to rotate in an anticlockwise direction such that the lead-screw 4b portion of the latter translates the platform 10 mounted thereon downwards as indicated by motion arrows in Figs. 8-9. As the platform 10 moves down, it drags the bur- holder 11 mounted thereon down as well, thus, drawing the bur Id, designated to be replaced, from the handpiece-head la. At the onset of the latter maneuver, the cam-follower 9d is initially situated at a central position on the spiral-cam-groove 8a ,and then, as the maneuver proceeds, the spiral-cam-disk 8 turns with the main-shaft 4 in an anticlockwise direction such that the spiral-cam-groove 8a translates the cam-follower 9d centrifugally, and the latter translates radially in its rail 9c until it makes contact with the cam-leader-flange 8b where, thence, the cam-follower 9d clings magnetically thereto. The angular position of the platform 10, and all parts mounted thereupon, is kept constant during the vertical translation thereof by a magnetic lock that exists between the radial-angular-Umiter 12, while fully extended, and the circumferential-collider 9b that corresponds to the angular sector of the bur being replaced as shown in Figs. 7-10. Once the cam-leader-flange 8b hits the cam-follower 9d, a magnetic lock develops between them and the latter is driven by the former in an anticlockwise direction, thus, driving the stage 9 and the circumferential-collider 9b thereof away from the radial-angular- limiter 12; this maneuver overcomes the magnetic lock that existed between the latter two. The anticlockwise rotation of the stage 9 also entails the anticlockwise rotation of the switch-cam 9a thereof such that the crest of the latter closes-then-releases the nearest of the N-series- microswitches, and then, closes-then-releases the next F-series-microswitch; the sequence in Fig. 11, for instance, is N8 then F7. At this stage, the closing and opening of the nearest anticlockwise N-microswitch is ineffectual, but the closing of the succeeding F-microswitch results in two simultaneous responses: the first being the reversal of polarity of the primary- motor 7 which, in turn, results in the immediate reversal of the direction of rotation of the main- shaft 4 into a clockwise direction; the second response being the activation of the linear- solenoid 13 which results in the rapid retraction of the radial-angular-limiter 12 from the path of the circumferential-colliders 9b as Fig. 3 illustrates the state thereof. At this point, the main- shaft 4 and the spiral-cam-disk 8 rotate in a clockwise direction, and due to the magnetic lock that was established in the last maneuver between the cam-leader-flange 8b and the cam- follower 9d, the stage 9 is now coupled to the spiral-cam-disk 8 in rotation and thus all related parts from the stage 9 to the bur-holder 11 rotate in a clockwise direction as one coherent unit. This causes the bur-set llf to rotate along with the latter from below the empty handpiece-head la. As this rotation proceeds, the switch-cam 9a keeps tripping the N-series and F-series- microswitches sequentially in a clockwise direction. The sequential closure and release of the latter microswitches proceeds ineffectually until the switch-cam 9a closes the N-microswitch which corresponds to the replacement-bur which was selected initially by the practitioner before the insertion of the handpiece 1; for example, if the practitioner chose the fifth bur in the bur-set 11 to replace the bur he already had on his handpiece 1, then he would have pushed the selection button B5, Fig. 12, on the selection panel before inserting the handpiece 1 and thus the clockwise sequential tripping of the N-series and F-series-microswitches by the switch-cam 9a proceeds ineffectually until the later closes the microswitch N5. The closure of the replacement-bur-corresponding-N-microswitch immediately deactivates the linear-solenoid 13 resulting in a spring-13b-actuated plunge-out of the plunger 13a along with the radial-angular- limiter 12 mated thereto. The latter, then, oversteps the path of, and attach magnetically to, the circumferential-collider 9b which corresponds to the sector of the replacement-bur, and, consequently, the stage 9 is stopped at an angulation such that the replacement-bur attains a position of axial collinear-alignrnent with the chuck of the handpiece-head la. As the main- shaft 4 continues to rotate in conjunction with the recent angular fixation of the stage 9, the magnetic lock between the cam-leader-flange 8b and the cam-follower 9d is overcome and the latter disengages from the former such that the spiral-cam-disk 8 rotates along with the main- shaft 4 leaving behind the stage 9 in its fixed angulation, and thus, driving the cam-follower 9d to slide centripetally by the spiral-cam-groove 8a. Simultaneously, as the main-shaft 4 continues to rotate in a clockwise direction, the lead-screw 4b elevates the platform 10 along with the bur-holder 11 mounted thereupon such that the replacement-bur Id slides up into the chuck of the handpiece-head la; Figs. 6-11 are depictive of the machine-state at the end of the latter maneuver when the replacement-bur Id was chosen to be the eighths bur of the bur-set llf.

At the point wherein the replacement-bur got fully inserted into the chuck of the handpiece- head la, the platform 10 would have reached its highest point and the switch-rim lOf thereof would have, then, closed the top-platform-stroke-limiter S3 microswitch.

The closure of the latter entails two immediate simultaneous responses: the first being the deactivation of the primary-motor 7 and, hence, a full stop of all rotary activity regarding the main-shaft 4 and all parts mounted thereupon; the second response being the activation of the secondary-motor 3h in a reverse direction such as to drive the fork 16 frontally outwards along with the handpiece-housing 15 mounted thereupon. The latter maneuver pushes the handpiece- head la forwards and, thus, drawing the replacement-bur Id mounted therein out of the grip of the bur-gripping-plate lib while, simultaneously, sliding the press-lever 15b from under the press-wheel 3c, thus, releasing the handpiece- push-button lc to allow the chuck to lock the replacement-bur Id therein firmly by the friction-grip thereof. Eventually, the fork 16 proceeds in a forwardly outward direction until it reaches a full halt upon the closure of the forward-fork- stroke-limiter SI microswitch by the switch-toggle-pin 16e. At that point, the practitioner may withdraw the handpiece 1, with the replacement-bur Id mounted therein, from the machine and canyon with his clinical procedure. The machine, at that point, has returned to its standby state once more, and, is ready for a new bur-replacement cycle.

The embodiment being described heretofore has a second variant customized to perform bur- changes on a wrench-type dental handpiece lw which, like the pushbutton-type, comprises a handle lb, a head la, and a mounted bur Id therein, but differs from the pushbutton-type in that the chuck thereof has a screw-bar socket, termed a wrench-socket le, which is actuated by the insertion, and turning, of a wrench-bar 15e therein. In this variant of the invention-embodiment, the provisions made to adapt the operation thereof to said wrench-type handpiece lw are illustrated in Figs. 13-16, said provisions consist in some limited additions and modifications of some mechanical elements such that, except for the mechanical interaction between the handpiece-housing-press-lever 15b and the press-wheel 3c, all said maneuvers of said embodiment during the automatic bur-changing cycle stays exactly the same as explained hereinbefore. In the present variant, the handpiece-housing-press-lever 15b features a spring-loaded- wrench- screw-bar 15e mounted thereupon perpendicularly by means of a supporting ramp-bracket 15d which also serves as a cam-like slide-presser for said handpiece-housing-press-lever 15b during the translation of the handpiece-housing 15 from the front to the rear during said functional maneuver explained hereinbefore. The wrench-bar 15e features a coaxial rubber- wheel 15f mounted thereupon such that the rotary motion of the former and the latter are coupled without relative freedom. Also in the present variant, the press-wheel 3c of the previous variant, is replaced by a flange of an inverted-L-shape cross-section wherein a flat vertical sheet, termed a vertical-friction-rack 3h, meets a flat horizontal sheet, termed a horizontal-press-flange 3j, such that both are fixed to the frame-top-piece 3.

The mode of operation of said modifications which characterize the present variant is as follows: once the handpiece-housing 15 starts its translation to bring in the handpiece lw into alignment with the axis of bur insertion dismounting as explained hereinbefore, the ramp- bracket 15d approaches, and contacts, the horizontal-press-flange 3j such that, as the maneuver advances, the former is forced to slide thereunder, thus, pressing the press-lever 15b to engage the counter-bur side of the handpiece-head la, while, simultaneously, the rubber-wheel 15f approaches the vertical-friction-rack 3h, and makes contact therewith, such that the former rolls thereon without sliding as illustrated by motion arrows in Fig. 15; the latter two maneuvers, simultaneously, bring the wrench-bar 15e into a position/orientation wherein the wrench-bar 15e is coaxial with the wrench-socket le and the cross-sectional-complementarity thereof coincide, thereby, springing the former into the latter as illustrated in Figs. 14,16. The full closure of the press-lever 15b concurrently constricts the handpiece lw to fit tightly into the handpiece-housing-dock 15a, thus, eliminating any relative play therein. As the handpiece- housing 15 proceeds to the rear limit of the translational stroke thereof explained hereinbefore, the rubber-wheel 15f rolls on the side of the vertical-friction-rack 3h thereby turning the wrench-socket le, via the wrench-bar 15e engaged therein, thus actuating the chuck of the handpiece lw. The latter mechanism actuates the chuck in a manner such that the friction-grip thereof is loosened as the handpiece-housing 15 is being pulled to the rear of the machine at the beginning of the bur-changing cycle, and, is tightened upon the converse maneuver at the end of the bur-changing cycle.